This paper describes a simple chemical co-precipitation method for preparing nano-sized zinc oxide (ZnO) nanospheres. The morphological, thermal, structural, and chemical features of ZnO nanospheres were systematically studied and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo gravimetric analysis-differential scanning calorimetric analysis, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. The SEM micrographs reveal that the particles are spherical in nature and the precipitating agent ammonia plays a critical role in controlling the morphology of the nanospheres. Crystalline ZnO phase is obtained at higher annealing temperature and there by reduce the contents of the hydrated species. Powder XRD pattern indicated that the nanospheres exhibit wurtzite hexagonal ZnO phase. The average crystallite sizes of the ZnO nanospheres were calculated to be 14 nm for as-prepared sample and 16 nm for 500 degrees C annealed sample. The peak broadening in ZnO nanospheres due to lattice deformation was analyzed by plotting various modified form of W-H analysis such as uniform deformation model, uniform stress deformation model, and uniform deformation energy density model. From the three models, the strain values epsilon and the crystallite size D(v) were estimated and tabulated. The growth and the formation of ZnO were predicted and the results were confirmed by FT-IR studies.